I feel like this is one of the poorer Snopes articles I’ve seen. His work was primarily post-Keynesian and focused on reformed and more equitable forms of capitalism.

Here’s his work from the late 70’s https://www.jstor.org/stable/27861872

I’d also argue that anyone that is teaching econ in college is going to be covering Keynes, Marx, etc. All the big influential economists get covered. You learn it all.